Register in useless opt the opt that remove node from the graph.

theano/tensor/opt.py

@@ -7490,29 +7490,20 @@ def local_useless_composite(node):
 # Although the ops ConsiderConstant, ZeroGrad and DisconnectedGrad
 # just returns the input, it should be removed from the graph to
 # make sure all possible optimizations can be applied.
-# TODO: Add in useless too!
-register_canonicalize(gof.OpRemove(theano.gradient.consider_constant_),
-                      'fast_compile', 'fast_run',
-                      name='remove_consider_constant')
-
-register_canonicalize(gof.OpRemove(theano.gradient.zero_grad_),
-                      'fast_compile', 'fast_run', name='remove_zero_grad')
-
-register_canonicalize(gof.OpRemove(theano.gradient.disconnected_grad_),
-                      'fast_compile', 'fast_run',
-                      name='remove_disconnected_grad')
-
-register_canonicalize(gof.OpRemove(theano.gradient.undefined_grad_),
-                      'fast_compile', 'fast_run',
-                      name='remove_undefined_grad')
-
-register_canonicalize(gof.OpRemove(theano.gradient.GradClip),
-                      'fast_compile', 'fast_run',
-                      name='remove_grad_clip')
-
-register_canonicalize(gof.OpRemove(theano.gradient.GradScale),
-                      'fast_compile', 'fast_run',
-                      name='remove_grad_scale')
+for opt, name in [(gof.OpRemove(theano.gradient.consider_constant_),
+                   "remove_consider_constant"),
+                  (gof.OpRemove(theano.gradient.zero_grad_),
+                   'remove_zero_grad'),
+                  (gof.OpRemove(theano.gradient.disconnected_grad_),
+                   'remove_disconnected_grad'),
+                  (gof.OpRemove(theano.gradient.undefined_grad_),
+                  'remove_undefined_grad'),
+                  (gof.OpRemove(theano.gradient.GradClip),
+                  'remove_grad_clip'),
+                  (gof.OpRemove(theano.gradient.GradScale),
+                  'remove_grad_scale')]:
+    register_canonicalize(opt, 'fast_compile', 'fast_run', name=name)
+    register_useless(opt, 'fast_compile', 'fast_run', name=name)
 
 
 @register_useless